In the event that it is believed that potentially hazardous chemicals are present in the ground, an important part of the remediation task is to determine the extent of the contamination. Preferably, a thorough investigation would include a complete mapping and subsurface analyses to assess the hazards and possible solutions. For example, cone penetrometer systems are known for performing subsurface analyses and are able to provide valuable information about the underground conditions and the extent of the contamination.
The cone penetrometer is typically a self-contained system carried by a truck so as to move into and around an area acquiring data from the ground. The system basically comprises powerful hydraulic rams for driving an assembled string, having sensors at the tip and along the string, down into the earth at a controlled rate to a depth of 100 feet or more.
During its passage into the ground, the string may pass through one or more zones containing hazardous chemicals and other zones that are free of such chemicals. Once the penetrometer investigation is complete, there is concern that the hazardous chemicals may travel along the various holes formed by the penetrometer string thereby significantly spreading the contamination. Clearly, the process of investigating the contamination should not cause or accelerate the spreading of such chemicals into such chemical free zones and increase the amount of remediation work to be done.
The current practice to avoid such spreading of the contamination is to seal the hole after completion of the cone penetrometer operations by injecting grout material therein. However, during the interim between the completion of penetrometer operations and grouting process, the hole has a tendency to collapse. The collapsing of the hole does not seal the hole or alleviate the likelihood of the chemicals propagating therealong into the other underground zones or strata. Thus, there is still a need to seal the hole. As such, the practice has been to position a grouting rig, provided with an auger bit, above the hole to bore down into the earth along the course of the penetrometer hole. The hole formed by the grouting rig is then filled with grout and left to dry and seal the hole. Unfortunately, the drilled hole does not reliably follow the cone penetrometer hole. Sealing a hole that deviates from the penetrometer hole does not provide an effective seal for the penetrometer hole. Accordingly, this device has not been fully satisfactory.
It is accordingly an object of the present invention to provide a method and apparatus for sealing holes in the ground which overcomes the aforementioned drawbacks and disadvantages of the prior art.